Heat treating method



July 25, 1961 K. F. BRAEUNINGER ETAL HEAT TREATING METHOD 5 Sheets-Sheet1 Filed Aug. 25, 1958 INVENTORS. Aar/ E firaeun/nger' Clare .5. HarrisF/TTORNEYS July 25, 1961 K. F. BRAEUNINGER ET AL 2,993,688

HEAT TREATING METHOD Filed Aug. 25, 1958 3 Sheets-Sheet 2 INVENTORS.Kar/ E Braeunr'nger Clare 6. Harris g i g HTTORNEKS July 25, 1961 K. F.BRAEUNINGER ET AL 2,993,688

HEAT TREATING METHOD Filed Aug. 25, 1958 5 Sheets-Sheet 3 52 I INVENTORS50 n 46 60 MIMI"! Aer/E firaeun/hyer C 0n? 6. Harvvls F2314 W2 MHTTOR/VEYS United States Fatent 2,993,688 HEAT TREATING METHOD Karl F.Braeuninger and Clare S. Harris, Ferguson, Mo., assignors to The DowChemical Company, Midland, Mich., a corporation of Delaware Filed Aug.25, 1958, Ser. No. 757,647 4 Claims. (Cl. 263-52) This invention relatesto heat treating furnaces and particularly to materials supporting andtransporting apparatus for horizontal furnaces which are used in heattreating light metal alloys such as alloys having a base of eitheraluminum or magnesium.

Extruded sections of light metal alloys and other heat treatablematerials often must undergo heat treatment before the sections aresuitable for final usage. Such heat treatment is usually accomplished ina horizontal type furnace. Horizontal furnaces are of two conventionaltypes as regards the supporting and transporting structure for thesections while they are within the furnace. In one type of furnace thesections which are to be heat treated are supported on closely spacedrollers which are oscillated constantly during the high temperaturecycle to prevent the extrudes from sagging between the rolls orotherwise becoming deformed by acquiring the imprint of the rollermember. The trouble encountered when such furnaces are used is thatsharp edges of the extnrdes which contact the rolls are damaged by beingflattened out until the contacting area is sufficient to bear, withoutfurther deformation, the weight of the extrude. This trouble isaggravated when the extrudes are crooked or twisted because suchconditions result in fewer rolls being in contact with the extrude.

In the other conventional or common type of horizontal furnace theextrudes are supported on a flat type conveyor. Although the conveyorsupport elements may be spaced close enough together to eliminatesagging or the flattening of sharp edges of the material being heattreated, the expansion of the extrudes due to temperature changes issuflicient to cause scufiing of the areas in contact with the supportelements.

Accordingly, a principal object of this invention is to provide animproved apparatus for transporting and supporting light metal alloys inheat treating furnaces in which the sections carried by the apparatusare subjected to less sagging, flattening, or scufling than has beenheretofore obtainable.

In accordance with this invention a horizontal type heat treatingfurnace is provided with dual acting apparatus for transporting andsupporting material to be heat treated in which the sections of metalwhich are to be heat treated are supported on rolls for the period ofheat treatment during which a large part of the thermal expansion of thetreated section occurs (before the section is greatly softened by theheat) and then is supported on transversely disposed, flat carrierelements or flow plates. The changeover from rolls to flat carrierelements is effected by relative vertical movement between the rolls andcarrier elements. The carrier elements may be stationary and the rollsmoveable, or vice versa. The moving apparatus is at the bottom of thefurnace structure and is connected to the elements to be moved throughsuitable linkage.

The invention, as well as additional objects and advan tages thereofwill best be understood when the following detailed description is readin connection with the accompanying drawings, in which:

FIG. 1 is a simplified-isometric view of materials supporting andtransporting apparatus made in accordance with this invention;

FIG. 2 is a side elevational view, partly in section, of apparatussimilar to that shown in FIG. 1 and in which the material carried by theapparatus is carried by the rolls;

FIG. 3 is similar to FIG. 2 except that the material is supportedprincipally by the floor plate of the apparatus, and

FIG. 4 is a diagrammatical view showing materials supporting andtransporting apparatus in which the rolls are raised and lowered and thefloor plate remains stationary.

Referring to FIGS. 1, 2 and 3 there is shown apparatus for transportingand supporting sections or sheets of material, usually but notnecessarily of metal, within a horizontal heat treating furnace (thewall enclosure of the furnace not being shown). The apparatus comprisesa plurality of roller members 10 which may be supported and driven, ifdesired, in any suitable manner. The rolls 10 are disposed parallel withrespect to one another and their horizontal axes lie in a common plane.Usually, out not necessarily, the rolls 10 are disposed perpendicularlywith respect to the centerline of the furnace (not shown) in which theapparatus is used.

Between each roll is a load supporting carrier section or floor plate 12having a planar upper surface 14. Each of the floor plates 12 aresecured to leg-like elements 16 which pass through bores 18 in a doublefaced base plate 29. Bushings or sleeves 22 are provided above and beloweach bore 18 to assure vertical alignment of the leg-like elements 16.Each of the leglike elements 16 has at its lower end a cap 24 whichrests on a coil spring 26. Each coil spring 26 rests upon a frame,indicated generally by the numeral 28, which includes (as shown moreclearly in FIG. 1) a pair of I beams 30 which are parallel and alignedwith the center-line (not shown) of the apparatus. The I beams 30 aresupported by transversely disposed beams 32. As shown in FIGS. 2 and 3(and as indicated by the arrows 34 in FIG. 1), means for raising andlowering the floor plates 12 with respect to the rolls 10, illustratedas jacks 36, are provided. The jacks 36 may be actuated hydraulically,mechanically or in any suitable manner. Alternatively, raising andlowering means in the form of cams or the like may be used. In FIG. 3the jacks are extended, raising the floor plates 12 level with the rolls10. It should be emphasized that the surface 14 of the plates 12 may beraised above the rolls 10, but this results in the loss of the rolls assupporting members.

The jacks 36 are disposed on suitable framing and supporting members 38,which are secured to the base plate 20 by hangars 40.

In operation the sheet or section 42 to be heat treated in the furnaceinitially rests upon the rollers 10. The rollers may be rotated in onedirection to carry the sheet or section 42 into the furnace and then therolls may be either oscillated or left free running during the time whenthe section or sheet is raised to, or near to, its softeningtemperature. The raising means, the jacks 36, are then actuated, raisingthe floor plates 12 as shown in FIG. 3 until most if not all of the loadof the section or sheet 42 is carried by the floor plates 12.

Since most of the expansion of the material in the furnace takes placebefore the material begins to soften, supporting the material on therollers 10 prevents the scufiing which would occur if the material weresupported during the entire heat treating cycle. Conversely, once thematerial softens, the floor plate supporting means prevents the saggingor distortion of thin elements or sections which often occurs if onlyrolls are used to support the material being heat treated.

This invention has thus far been described as apparatus in which thefloor plates are raised and lowered with respect to the rolls. FIG. 4shows, in diagrammatical form, apparatus in which the rolls are raisedand lowered with respect to the floor plates.

In FIG. 4 the floor plate assembly 44 is secured to a base plate 46 bythe supporting member(s) 48. Jacks 50 (or other suitable raising andlowering means), mounted on the base 46, support a roll supporting frame52. Motors 54 or other suitable drive means which may be synchronized inspeed are coupled through chain belts 56, for example, to pulleys 58 onthe shaft 60 of each roll 62. The operation of the apparatus shown inFIG. 4 as regards the way material is handled is generally the same asthat of FIGS. 1, 2 and 3 except that the rolls 62 rather than the floorplate assembly 44 is raised and lowered.

While the illustrated embodiments of the invention show the mechanismsfor raising or lowering the rolls or floor plate being at the lower partof the apparatus, the raising or lowering could be accomplished by meansof retractable rods or cables, for example, extending downwardly fromabove the rolls. Further, relative movement between the floor platesurface and rolls may be accomplished by movement of both the rolls andfloor plates.

This application is a continuation-in-part of my copending applicationSerial No. 688,043, filed October 3, 1957, now abandoned.

What is claimed is:

1. The method of supporting a light metal section in a horizontallydisposed heat treating furnace during a heat treating cycle during whichthe section is heated at 2,993,688 H g V 4 least near to the range oftemperature where softening of the section occurs, comprising supportingthe section within the furnace solely on roller-s during the heatingcycle until the section approaches its softening temperature range, thensupporting the major port of said section on flat surfaces between saidrollers while said section is heated to its softening temperature range,and again sup porting said section solely on rollers when said sectionis cooled below its softening temperature range.

2. The method of claim 1, wherein during the part of said heat treatingcycle in which the section is soft the section is supported by said flatsurface and by said rollers.

3. The method of claim 1, wherein said light metal section istransported into and out of said furnace on said rollers.

4. The method of claim 1, wherein said rollers are free to rotate duringsaid heat treating cycle.

References Cited in the file of this patent UNITED STATES PATENTS1,205,690 Wetcke Nov. 21, 1916 2,875,995 Troglione Mar. 3, 19592,883,172 Mitchell Apr. 21, 195 9 FOREIGN PATENTS 493,184 Great BritainOct. 4, 1938 516,683 Great Britain Ian. 9, 194.0

